With the progress of transistor process technology, the dimension of transistors has shrunk and therefore the number of transistors per unit area of an integrated circuit has increased accordingly. However, the off-state current has dramatically increased with further reduction in the channel length of a transistor, i.e., short channel effect. This effect is the major challenge of further increasing the density of transistors for transistors' channel length less than 20 nm. Reducing the thickness of channel is known as one way of suppressing short channel effect. Ultra-thin body transistors may employ ultra-thin semiconductor channel materials to suppress the short channel effect. 2D semiconductors are expected to be the channel material in ultra-thin body transistors. Two dimensional materials, such as transition metal dichalcogenides, graphene, and black phosphorus are regarded as promising candidates for transistor channels in FET devices. Conventional methods of fabrication of FET devices may be incapable of controlling the layer thickness and interface composition with atomic precision, which is of paramount importance in the fabrication of future generation of nano-electronic devices.
Solutions are required that can achieve a desired interface between gate dielectric layers and 2D channel materials with an ultra-thin body thickness, which can be less than about one-quarter of a respective gate width (e.g., 20 nm).